Automatic meter reading apparatus



June 15, 1943. W.'LEATHERS 2,321,922

AUTOMATIC METER READING APPARATUS OriginalFiled Oct. 18', 1940 "INVENIOR.

Patented June 15, 1943 AUTOMATIC mam alanine mans-ms Ward Leathers, Brooklyn, N. 1.. assignor a lilternationai Business Machines Co rporation,

New York, N. Y., a corporation or New York Original application October 18, 1940, Serial No. 1,801, new Patent No. 2,285,819, dated June 9,

1942, Serial No. 439,539

1 Claim. (Cl. 177-453) The present invention relates to electric 8 naling and indicating systems or the type wherein the position or a movable member, such as, 101' example, a meter pointer or other indicator may accurately be determined at a remote point by a resistance measuring method.

More specifically the invention relates to a telemetric system which is fully automatic inits operation and wherein the relative positions, and consequently the relative indications, of a plurality oi movable meter pointers or other indicating members, each associated with a respective meter unit, which units may be widely separated, may successively be determined and caused to be registered, recorded or otherwise indicated by a resistance measuring process at a central station without necessitating the use of individual lines for each indicating member. Such a system is fully illustrated and described in my prior Patent No. 2,285,819, dated June 9, 1942, for Automatic meter reading apparatus, of which this application isa division.

The objects of the present invention as disclosed herein are in general the same as the objects set forth in my prior patent wherein there was claimed a means for individually selecting a large number of meters for reading purposes and !or subsequently causing the selected meters to be read by a resistance measuring process at a central station over a simplified wire system by the expedient of utilizing primary and secondary selectors capable of being selectively actuated by the application of current impulses of different characteristics.

A further object of the invention, in one form thereof, is to provide a fully automatic telemeter- ,ing system of the character set forth above wherein a plurality of outlying stations, each having associated therewith a meter to be read, and connected together in a simple parallel circuit, may be selected in succession by application to the circuit at a central station of aseries or current impulses of varying voltage and of opposite polarity. and an indication of the respective meters thereof rendered at the central station, the whole process being entirely automatic in its operation.

In carryins out the above mentioned objects, briefly, the invention contemplates the provision of a series of heavily damped current measuring devices which are located at the central station and which correspond in number to the number of meters at the respective outlying positions. The various meters are capable, potentiallv, being electrically connected in parallel Divided and this application April 18,

in a reading circuit leading to the central station. Each meter has associated therewith at its respective outlying position, a marginal relay device and a unidirectional device which are so arranged that current impulses of varying volt age'or of opposite polarity will selectively actuate the relays preferably in a sequential manner to connect their respective meters in the readin circuit for reading purposes by a resistance measuring method. Successive selection of the various meters for reading purposes is accompanied by substantially instantaneous electrical connection thereof to their respective current measuring devices by means of a step-by-stcp I multiplexing device or selector switch located at the central station and such connection renders the current measuring device instantly indicative of the resistance of the successively selected meters or determined by the respective indications thereof.

Other objects and advantages of the invention will become more readily apparent as the nature of the invention is better understood.

In the accompanying drawing forming part of this specification, the figure is a diagrammatic view of the telemetering system showing a central station and a plurality of outlying stations electrically connected in parallel and to the central station,

In th above described view, similar characters of reference have been employed to designate similar parts throughout.

Referring now to the figure, wherein one embodiment of the invention is shown, a central station generally characterized by the numeral I0. is connected to a plurality of outlying stations, each including a variable resistance generally characterized by the numeral I39, by means of a reading conductor H9 having a battery H8 interposed therein, and a selector conductor I03. A multiplexing device in the form of a selector switch I consists of an annular series of contacts I05, a rotary contact arm or brush Ill therefor, and a second annular series of contacts I spaced inwardly from the series I", together with a second rotary contact arm or brush III! for the latter series of contacts. The contact arms ill and I are designed for rotation in phase relationship about a central axis and are driven in unison by a motor H0 adapted to be energized from a source of current, as, for example, a battery iii. The selector line I is connected to the brush i and thus is adapted to be connected to each of the contacts I" successively when the motor III is in operation.

I02 are reversedin polarity, the battery I02 making the line I03 negative and the battery I02 making the line I03 positive with respect to ground potential. Since each contact I 05 taps a different voltage from the batteries I02 and I02, the line I03 will alternately assume varying po-- tentials of opposite polarity as the brush I00 rotates about its central axis. I I

While only four outlying stations I21, I22, I23 and I24 have been shown in the accompanying drawing it will be understood, however, that a greater or lesser number of these stations may be employed, if desired.

The application of a ten volt impulse to the selector line I03 from the central station I00 in such a manner as to make the line I03 positive with respect to ground will serve to energize a relay I21 at the outlying station I2I which is responsive to a minimum voltage potential of ten volts and cause its armature I29 to close a pair of contacts I30. The ten volt impulse will also be applied to a relay I which is connected in parallel with the relay I21. The relay I20, however, is responsive to a minimum voltage poten-- tial of fifteen volts and therefore it will not become actuated when an impulse of only ten volts is applied to the selector line I 03. Therefore. upon application to the line I03 of a selecting impulse of ten volts of a proper polarity, the contacts I30 will become closed, thus completing a local circuit containing a battery or other source of current I and a relay I30. Completion of the circuit through the relay I36 serves to close a pair of contacts I30 contained in a reading circuit including the line II9, battery H0 and variable resistance I39a. The contact arms I00 and I09 are arranged to maintain a constant phase relationship, and thus the meters II3, II4, etc., at the central station I04, each of which corresponds to a variable resistance I39 at the outlying station I2I, will upon successive closing of the contacts I30 be successively connected in the reading circuit and the portion of each resistance I39 contained inv the circuit will be indicated in terms of current flow through a corresponding meter I I3 at the central station I00.

The outlying station I22 is also adapted to be actuated by application to the line I03 of an impulse of ten volts but of opposite polarity, i. e., an impulse which will render the line I03 negative with respect to ground. A copper-oxide rectifier I25a in series with the relays I21 and I20 in the outlying station I2I permits only current of a character that will make the line I03 positive with respect to ground to affectthe relays I21 and I20. A copper-oxide rectifier I25b, similarly connected at the station I22, permits only current that will make the line I03 negative with respect to ground to afi'ectthe relays in this latter station. Upon closing of the local circuit in the station I22 the variable resistance I39b thereof is reflected by a reading ,of a corresponding meter H4 at the central station.

Application of an impulse of fifteen volt potential to the line I03 from the central station I00 in such a manner as to make the line I03 positive with respect to ground will serve to cause the station I23 to be selected for actuation. A relay I40 designed to actuate upon application thereto of a fifteen volt impulse will, upon energlzation, cause an armature I to close a pair pulse of not less than twenty volts. A copperoxide rectifier I250 prevents current of opposite polarity, regardless of its potential, from aflecting the relays I40 and I43. Thus, when an impulse of fifteen volts potential, which will make P the line I03 positive with respect to the ground,

is applied to the line I03, a relay I41 is energized b means of the battery I46 contained in a local circuit, and a pair of normally open contacts I49 become closed to establish a reading circuit for the resistance I39c in the manner previously described in connection with the variable resistances I39a and I33b in the outlying stations I2I and I22 respectively, so that its indication may be reflected by its corresponding meter H5 in the central station I00.

The application to the line I03 of an impulse of fifteen volts in such a manner as to make the line I03 positive with respect to ground, in addition to actuating the outlying station I23 also serves to energize both of the relays I21 and I20 of the station I21. Since the relays of this latter station are receptive to current impulses of the same polarity, however, the relay I20 becomes fully energized in such an instance and causes the armature I3I to open the contacts I32 and thus open the local circuit of the relay I30 and prevent the variable resistance I39a from being connected in the reading circuit leading to the central station through the reading line H9.

Numerous additional stations may be included in the series I2I, I22, etc., and it is thought that the manner of their inclusion therein will be apparent without further description. Application of impulses to the selector line I03 in steps of five volt potential differentials will serve for the selection of either one of two stations depending upon the polarity of the applied impulse.

Assuming that the potential of the highest selector impulse employed in the system is one hundred volts, there may be two stations which are capable of actuation by such an impulse, depending upon the olarity'thereof. In the accompanying drawing only one such end" station is shown in the interest of simplicity. These end stations differ from the preceding stations in that they require only one relay.

The station I24 represents an end station which becomes actuated when a pulse of one hundred volts of such polarity that the line I03 is rendered negative with respect to ground. In case of the application of such pulse, a relay I52 becomes fully energized and causes an armature I53 to close a pair of contacts I54 thus connecting a variable resistance I39d.directly into the circuit for reading purposes by means of a corresponding meter at the central station I00. A copper-oxide rectifier l25d prevents an impulse of one hundred volts of opposite polarity from afiecting the relay I52.

The contact arm or brush I03 alternately multiplexes or successively connects the selector I in constant phase relationship, or, in other words, are rotated in unison so that each outlying station I2 I, I22, etc., is selected successively for connection to a respective reading meter I I3, I I4, etc. The battery H0 and the line Ill supplies the reading current whereby each measuring meter will render an indication proportionate to a variable resistance 9 at its respective outlying station.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawing or described in this specification as various changes in the details oi construction may be resorted to without departing from the spirit of the invention. For example, while the receiving apparatus at the central station utilizes a power driven multiplexing switch for fully automatic selection of the various outlying stations, it is obvious that if desired a manually operated selector device may be employed for random selection of the stations. Only insofar as the invention has particularly been pointed out in the accompany ins claim is the same to be limited.

What is claimed is:

In a telemetric system, apparatus for selectively closing at a central station a series of normally open local circuits each located at an outlying station, comprising a normally open switch and a normally closed switch arranged in series in each local circuit, a solenoid for each switch, said solenoids being operable upon energization thereof to open the normally closed switch and to close the normally open switch respectively, a

selector circuit including a main channel connected to the central station and branch channels connected to the main channel in parallel relationship and each connected to and serving an outlying station, the solenoids of each outlying station being connected in parallel relationship in a respective branch channel, the solenoids of each outlying station being responsive to direct current impulses of diflerent voltage charac-' teristics for actuation thereof, the solenoids of certain successive alternate outlying stations being responsive to current impulses of difl'erent but progressively higher voltage characteristics for their actuation and the solenoids of other successive alternate outlying stations also being responsive to current impulses of diilerent but progressively higher voltage characteristics for their actuation, the solenoids of said first alternate series of outlying stations being responsive to unidirectional current of one polarity and the solenoids of said second alternate series 01 outlying stations being responsive to unidirectional current of opposite polarity, and means at the central station for successively applying current impulses of progressively increasing voltage characteristics and of opposite polarity alternately to the main channel.

, WARD LEATHERS. 

